Common domestic water taps comprise a tap body having a fluid flow pathway extending therethrough, a valve seat located intermediate the fluid flow pathway, a tap spindle moveable towards and away from the valve seat which includes an axial recess, and a tap head which connects to the tap body and which houses the tap spindle. The tap head includes an opening in the top through which an upper portion of the tap spindle extends and on which a handle is fitted to permit the tap spindle to be rotated in the tap head and thereby move either towards or away from the valve seat.
Valves which are commonly used with this type of tap are known as tap washers and comprise a disc-like seal which overlies the valve seat, and a stem which extends from the disc-like seal and locates within the tap spindle. Thus, movement of the tap spindle towards the valve seat causes the disc-like seal to be brought into engagement with the valve seat to thereby stop the flow of water through the tap body.
Such disc-like seals have a number of disadvantages, prime among which are their proclivity to rapid wear, leading to a relatively limited life span. Furthermore, it is quite common for particulate debris to trapped on the disc so that a firm sealing cannot be achieved and dripping occurs.